Tropics
Online ISSN : 1882-5729
Print ISSN : 0917-415X
ISSN-L : 0917-415X
Volume 3, Issue 1
Displaying 1-9 of 9 articles from this issue
  • 1994 Volume 3 Issue 1 Pages 1-2
    Published: 1994
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
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  • Potential of Sawah Based Agriculture in Tropical Africa
    Toshiyuki WAKATSUKI
    1994 Volume 3 Issue 1 Pages 3-17
    Published: 1994
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    Fertile soils and ample water cycling sustain human life on the earth. The distribution of fertile soils, and hence the distribution of population, are related to the amount and quality of geological fertilization processes. The geological fertilizations are 1) transport and sedimentation of eroded soils by river water, 2) volcanic activities to supply fresh easily weatherable volcanic ashes. 3) formation and transport of aeolian dust, and 4) dynamic balance between soil erosion and soil formation. Major soils in tropical Asia are generally active and fertile. In addition to favorable soil distribution, Sawah based rice agriculture using lowland Inceptisols is common. In the sawah agriculture the 1st. geological fertilization process is strengthened artificially. Major soils of tropical Africa are non productive Oxisols. Aridisols and Psamments which occupy 65% of total area. Major soils for agricultural production are Alfisols and Ultisols, which are suffering either water shortage or nutrients depletion. If we consider the such soil characters. the effective population density of Africa become 150 persons/km2, which is a similar level of that of tropical Asia. The effective population density of tropical America was 50 persons/km2. Past twenty years agricultural productivities were doubled in tropical Asia, whereas. although the population density doubled, the agricultural productivities have been stagnated in tropical Africa. Soil degradations and desertifications are accelerating. Why has the green revolution not yet realized in Africa despite the successful experience in tropical Asia. The author hypothesizes that the key issue is general underdevelopment of lowland agriculture in tropical Africa. The “environment creative technology”, such as sawah farming is lacking in sub-Sahara Africa. Therefore irrigation was not efficient and thus development was slow, which made it difficult to use fertilizer efficiently, and accordingly high yielding varieties were useless. The sawah based farming is an intensive and sustainable system. Sustainable roductivity of 1 ha of sawah may be equivalent to more than 10 ha of upland field. If we can expand the sawah based farming in tropical Africa we will be able to alleviate present crises of environment and agriculture in tropical Africa. Therefore the cooperation between tropical Asia and tropical Africa will be important not only for sustainable development of agriculture but also for creating our new global societies.
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  • Sadao SAKAMOTO
    1994 Volume 3 Issue 1 Pages 19-32
    Published: 1994
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    Tubers and millets are crops domesticated mainly for starch food sources. The former group reserves starch in vegetative organs, such as tubers, corms or roots, but the latter does so in grains. This clear difference can be attributed to the difference in their places of origin, namely, the former mainly in the moist subtropics or tropics while the latter originated mainly in temperate or subtropical steppes or savannas. The so-called tuber plants include more than 1,000 species found both in wild and cultivated states. This attests to our long history of utilizing tubers as important staple food materials. In this article tuber crops are defined in the narrow sense as domesticated plants which reserve starch mostly in underground organs. The representative eleven tuber crops grown in wide areas of the world are listed in Table I. Tubers can be characterized by the following traits: (I) easy management for cultivation and harvesting, (2) difficulty in long-termed preservation, (3) high water content and (4) easy cooking. Tubers have played an important role in eating habits which is closely related to the crop rotation system in shifting cultivation and also in agricultural rituals. Among tuber crops, the potato is a very important food in the arctic-temperate regions of the world, sweet potato and cassava are highly valued in the tropics, and taro, yautia and the greater yam are grown together with Guinea yams in tropical West Africa.
    The main cereals now cultivated extensively in the world include wheat, rice, maize and barley. It is usually considered that we are dependent on these four major cereals, but these cereals have become our staple food only quite recently. People have also grown many other cereals as staple food sources. Those cereals are mostly known as millets. They can be defined as a group of gramineous crops which have small grains and are cultivated mainly as summer crops in savanna-like environments of semiarid tropic or subtropic regions and in temperate monsoon regions. A great variety of millets are known in the world, and Table 2 gives the scientific name, tribe, common name and the place of origin for the twenty main millets. As evident from the table, these millets originated chiefly from Eurasia and Africa. The most important areas of domestication are East Asia, the Indian Subcontinent and the regions from the southern margin of the Sahara to the Ethiopian highlands in Africa. Different kinds of millets were domesticated in these two continents. Foxtail millet, common millet, Japanese barnyard millet, Indian barnyard millet and Job's tears are representatives of the millets which originated in Eurasia; sorghum, finger millet and pearl millet represent the African millets. Even in those areas where rice, wheat, maize or other major cereals are prevalently cultivated nowadays, history tells us that millets were rated highly in the past, playing traditionally an important role in our diet. This is because millets have a number of merits. First of all, millets can grow well even in those districts where soil, climate and other conditions are unfavorable. They are tolerant to excessively dry fields and infertile soils. Though their grains are small in size, their yield is stable. Secondly, when millets are bound and stored without threshing, they can be kept for a long time without much damage from insect pests. Because of this merit, they play the role of an emergency crop in years of bad harvest. Thirdly, many methods of using millets have been established as the materials of traditional staple foods. Fourthly, millets are used as the materials of making local drinks. This is closely related to the farming practice, dietary culture and agricultural rituals of rural communities. Finally, many millets have not attracted much attention by agronomists, and few attempts of modem breeding have been made. Thus, local landraces are still grown in many areas of the world.
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  • Yo-Ichiro SATO
    1994 Volume 3 Issue 1 Pages 33-50
    Published: 1994
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    Vanishing of genetic resources within a cultivated plant species, genetic erosion, has been recognized as a serious problem in the field of agronomy. To estimate the rate of genetic erosion in wild rice, biomass (product of total area of the population X rice plant cover in percent) of 21 wild rice populations in northern and northeastern Thailand was measured in 1983 and 1991 (or 1992). The biomass of nine annual populations reduced to 13 percent during this decade, suggesting that they will vanish by the end of this century. The biomass of twelve perennial populations reduced to 73 percent. In perennial populations, weedy type caused by the introduction of genome of the neighbouring cultivars is increasing. Pure perennial wild rice is now being replaced by the weedy type. Genetic erosion occurs in cultivated rice also. Number of native varieties grown in northeastern Thailand reduced approximately to 50 percent during this decade. Genetic diversity within a field was also reduced as the introduction of high-yielding varieties. To prevent progress of the genetic erosion, gene banks were established for preservation of the genetic resources for major cultivated plant species, i.e., rice, wheat, corn, barley, beans. In case of rice, gene banks were built at the International Rice Research Institute (lRRI). National ones were also built in various countries. Gene banks have been playing important roles for preventing the vanishing of the genetic resources. However, they do not play effectively to maintain genetic diversity in agroecosystems. In situ conservation of the genetic resources, that is a new way of conservation in agroecosystem, is preferred. From the viewpoint of agronomy, low input sustainable agriculture(LISA) should be encouraged to keep agroecosystem sustainable.
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  • Cattle coat-color and sorghum variation
    Katuyoshi FUKUI
    1994 Volume 3 Issue 1 Pages 51-70
    Published: 1994
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    The present paper intends to illustrate how human cognition has co-evolved with the selection of diverse domesticates, by examining the ethnographic materials from the Bodi (Me?en) in southwest Ethiopia. The color polymorphism is said to be one of the most distinguished characteristics of those domesticates. This may be a result of not only the intention that man would control the animal and plant reproduction, but also the way in which he has recognized various phenotypes of genetic variants and included them into his culture. That is, the color polymorphism that arose in the process of domestication is needed for the cultural phenomena of human beings as well as the biological ones of animals and plants.
    In East Africa including Ethiopia and Sudan, we can find tremendous varieties of animal coat-color as well as of sorghum. The author made an intensive survey among the Bodi, who depend mainly on cattle and goats together with sorghum, from the cultural anthropological point of view in 1973-6 and 1991. He has found several significant points on the interrelationship between human cognition and color polymorphism
    1) The color-pattern cognition among the Bodi is formed on the basis of their folk classification of cows with reference to their coat colors.
    2) The cattle are named on the basis of their coat colors, and they are genealogically traced even over sixteen generations.
    3) Most of the cases of crossing are recognized and remembered as long as the Bodi keep their cattle in their compound. They have constructed their own folk genetics by countless observations, namely the cognition of crossing and the resultant hybrids from generation to generation. The Bodi are able to predict, by means of their folk genetics, what kinds of animal coat-color will be the result from crossing some kinds of animal coat-color. Their folk genetics has been recently verified by animal geneticist, Nozawa (in press).
    4) The Bodi identify themselves with the cattle and sorghum through particular colors of variation, which are decided by their naming system, and also use animals according to their coat-colors at various kinds of rituals (Table 5).
    5) In order to produce offspring with particular kinds of coat-colors for their identification and their usage at rituals, the Bodi keep the bulls with particular coat-colors in their compound.
    It is quite obvious that many kinds of animal coat-color as well as sorghum are indispensable to the Bodi society. Without such variations, it is doubtful that the Bodi could exist socially and culturally. We may say that the Bodi people promoted the diversified selection of animal coat-colors as well as sorghum color by their own cultural devices. Such a study on color polymorphism in contemporary societies may make an important contribution to the analysis not only of the process of domestication, but also of the interrelationship between nature and culture in human society.
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  • 1994 Volume 3 Issue 1 Pages 71-77
    Published: 1994
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
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  • Kazutaka NAKANO
    1994 Volume 3 Issue 1 Pages 79-86
    Published: 1994
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    The inhabitants in Melanesia which contains the largest island of the tropics, New Guinea, and other larger ones than those in Polynesia and Micronesia, seem more active for agricultural production than in the other regions mentioned above. When we analyze the structure of the agricultural system in Melanesia, it is convenient, just as in the cases of most developing countries in the tropics, to divide it into two sectors, i. e., commercial agriculture and subsistence production. Most of the researchers engaged in the various aspects of subsistence agriculture in Melanesia, which is very often called horticulture conventionally by Westerners, agree on the view that the staple foods of the majority of the inhabitants there have been Colocasia taros and yams since very old limes. In some areas, however, the people have been ingesting mostly sago starch or bananas including plantains. Besides these crops, other fruits, such as coconuts and bread fruits, have also been very frequently consumed by Melanesians as well as Polynesians and Micronesians. Talking about the present situation of subsistence agriculture or horticulture in many regions of Melanesia, we cannot disregard the great and growing importance of sweet potato and cassava as the inhabitants’ basic sources of food energy. Of these two crops, in some regions, the former has been maintaining the position of staple food from an old or relatively recent time. For example, according to the popular view, more than 300 years have already elapsed since the primary food in the New Guinean Highlands changed from taros and/or yams to sweet potatoes. The data on the basis of FAO sources in the first half of the 1980’s elucidated that the leading country for the per capita production of sweet potatoes (193 kg/year) was the Solomon Islands. In that country, however, it was not a very ancient date but around 1960 that sweet potato was considered to become the crop for the staple food of most people there. This is endorsed by many reports having been published since the 1950’s. The major and direct reason for the change of the primary crop in the Solomon Islands was the spread, throughout that country, of pathogenic blight-producing fungi and of a beetle pest both of which are specific to taros. In addition to this direct reason, however, the following circumstances are considered to have certainly related to the preceding change:
    ...
    Summarizing these respects stated above, sweet potatoes are surely superior to taros or yams concerning labor productivity and security in the sense that the farmers rarely lack their subsistence requirements. This is probably the prime reason why the cultivation of sweet potatoes has become immensely and widely popular in the Solomon Islands from the 1950’s. The change of the staple food of the inhabitants there needed a trigger such as the spread of pest and blight but was, however, basically due to changes of social circumstances.
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  • Michiko INTOH
    1994 Volume 3 Issue 1 Pages 87-108
    Published: 1994
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    There are some environmental variations between volcanic islands and coral islands in the Pacific. When the Austronesian population dispersed into Oceania around 1600B.C., they brought a set of cultural complexes which included a wide range of material cultures. Various efforts were made to retain these cultural complexes by making efforts in looking for similar materials or importing unobtainable materials from remote islands. The early settlers also took similar colonization strategies at various islands. These are: exploring a new environment to look for useful resources; hunting birds, shell fishing and gathering wild plants; and land clearing by fire in order to cultivate plants brought from Southeast Asia.
    About several hundred years after colonization, many activities employed during this early period have changed: more reliance on domesticated plants and animals; replacing resources imported from remote islands with ones from nearer islands; development of sophisticated agricultural systems adapted to each island environment, etc. These adaptive changes have developed differently, corresponding to each island environment as well as to cultural preferences of each population group. After such adaptive changes made in many islands, the similar cultural complex possessed by early populations has become divergent as a whole.
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  • Yasuyuki KARAKIT A
    1994 Volume 3 Issue 1 Pages 109-120
    Published: 1994
    Released on J-STAGE: August 31, 2009
    JOURNAL FREE ACCESS
    This paper reports the complementarity between two kin categories, i.e. laiul mwal (children of men) and laiul shoabut (children of women), found in the formation of land-holding groups in Falalap, Woleai Atoll, Central Caroline Islands. The fundamental units in Falalap social structure are matrilineal clans (gailang) and matrilineages or uxorilocal extended families. However, according to Falalap people, one does not belong exclusively to mother’s group, but to both mother’s and father’s groups. Two categories are recognized among the members of a matrilineal clan. The children of male members are called laiul mwal (children of men) and the children of female members are called laiul shoabut (children of women). These two categories show oppositions in the complementary contexts of respect-avoidance behaviors and the formation of land-holding groups. Strict respect-avoidance behaviors are stipulated between brothers and sisters. In this context, the children of men are superior to the children of women. On the other hand, in the formation of land-holding groups, the children of women are superior to the children of men. A segment is formed only when certain members within a lineage receives land from their father's lineage. When the children of men received certain land from their father's group, they had certain obligations towards their father's group before World War II. When the children of men could not meet these obligations, the children of women could chase the children of men out. This relation between the children of women and the children of men is in sharp contrast with the cross-sibling relationship in the respect-avoidance behaviors, so that it is possible to say the crosssibling relation in Falalap, Woleai shows complementarity across the contexts.
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